There are many ways to troubleshoot the ingress-controller. The following are basic troubleshooting methods to obtain more information.
Check the Ingress Resource Events
$ kubectl get ing -n <namespace-of-ingress-resource>
NAME HOSTS ADDRESS PORTS AGE
cafe-ingress cafe.com 10.0.2.15 80 25s
$ kubectl describe ing <ingress-resource-name> -n <namespace-of-ingress-resource>
Name: cafe-ingress
Namespace: default
Address: 10.0.2.15
Default backend: default-http-backend:80 (172.17.0.5:8080)
Rules:
Host Path Backends
---- ---- --------
cafe.com
/tea tea-svc:80 (<none>)
/coffee coffee-svc:80 (<none>)
Annotations:
kubectl.kubernetes.io/last-applied-configuration: {"apiVersion":"networking.k8s.io/v1","kind":"Ingress","metadata":{"annotations":{},"name":"cafe-ingress","namespace":"default","selfLink":"/apis/networking/v1/namespaces/default/ingresses/cafe-ingress"},"spec":{"rules":[{"host":"cafe.com","http":{"paths":[{"backend":{"serviceName":"tea-svc","servicePort":80},"path":"/tea"},{"backend":{"serviceName":"coffee-svc","servicePort":80},"path":"/coffee"}]}}]},"status":{"loadBalancer":{"ingress":[{"ip":"169.48.142.110"}]}}}
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal CREATE 1m nginx-ingress-controller Ingress default/cafe-ingress
Normal UPDATE 58s nginx-ingress-controller Ingress default/cafe-ingressCheck the Ingress Controller Logs
$ kubectl get pods -n <namespace-of-ingress-controller>
NAME READY STATUS RESTARTS AGE
nginx-ingress-controller-67956bf89d-fv58j 1/1 Running 0 1m
$ kubectl logs -n <namespace> nginx-ingress-controller-67956bf89d-fv58j
-------------------------------------------------------------------------------
NGINX Ingress controller
Release: 0.14.0
Build: git-734361d
Repository: https://github.com/kubernetes/ingress-nginx
-------------------------------------------------------------------------------
....Check the Nginx Configuration
$ kubectl get pods -n <namespace-of-ingress-controller>
NAME READY STATUS RESTARTS AGE
nginx-ingress-controller-67956bf89d-fv58j 1/1 Running 0 1m
$ kubectl exec -it -n <namespace-of-ingress-controller> nginx-ingress-controller-67956bf89d-fv58j -- cat /etc/nginx/nginx.conf
daemon off;
worker_processes 2;
pid /run/nginx.pid;
worker_rlimit_nofile 523264;
worker_shutdown_timeout 240s;
events {
multi_accept on;
worker_connections 16384;
use epoll;
}
http {
....Check if used Services Exist
$ kubectl get svc --all-namespaces
NAMESPACE NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
default coffee-svc ClusterIP 10.106.154.35 <none> 80/TCP 18m
default kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 30m
default tea-svc ClusterIP 10.104.172.12 <none> 80/TCP 18m
kube-system default-http-backend NodePort 10.108.189.236 <none> 80:30001/TCP 30m
kube-system kube-dns ClusterIP 10.96.0.10 <none> 53/UDP,53/TCP 30m
kube-system kubernetes-dashboard NodePort 10.103.128.17 <none> 80:30000/TCP 30mUsing the flag --v=XX it is possible to increase the level of logging. This is performed by editing
the deployment.
$ kubectl get deploy -n <namespace-of-ingress-controller>
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
default-http-backend 1 1 1 1 35m
nginx-ingress-controller 1 1 1 1 35m
$ kubectl edit deploy -n <namespace-of-ingress-controller> nginx-ingress-controller
# Add --v=X to "- args", where X is an integer--v=2shows details usingdiffabout the changes in the configuration in nginx--v=3shows details about the service, Ingress rule, endpoint changes and it dumps the nginx configuration in JSON format--v=5configures NGINX in debug mode
A number of components are involved in the authentication process and the first step is to narrow down the source of the problem, namely whether it is a problem with service authentication or with the kubeconfig file.
Both authentications must work:
+-------------+ service +------------+
| | authentication | |
+ apiserver +<-------------------+ ingress |
| | | controller |
+-------------+ +------------+
Service authentication
The Ingress controller needs information from apiserver. Therefore, authentication is required, which can be achieved in two different ways:
-
Service Account: This is recommended, because nothing has to be configured. The Ingress controller will use information provided by the system to communicate with the API server. See 'Service Account' section for details.
-
Kubeconfig file: In some Kubernetes environments service accounts are not available. In this case a manual configuration is required. The Ingress controller binary can be started with the
--kubeconfigflag. The value of the flag is a path to a file specifying how to connect to the API server. Using the--kubeconfigdoes not requires the flag--apiserver-host. The format of the file is identical to~/.kube/configwhich is used by kubectl to connect to the API server. See 'kubeconfig' section for details. -
Using the flag
--apiserver-host: Using this flag--apiserver-host=http://localhost:8080it is possible to specify an unsecured API server or reach a remote kubernetes cluster using kubectl proxy. Please do not use this approach in production.
In the diagram below you can see the full authentication flow with all options, starting with the browser on the lower left hand side.
Kubernetes Workstation
+---------------------------------------------------+ +------------------+
| | | |
| +-----------+ apiserver +------------+ | | +------------+ |
| | | proxy | | | | | | |
| | apiserver | | ingress | | | | ingress | |
| | | | controller | | | | controller | |
| | | | | | | | | |
| | | | | | | | | |
| | | service account/ | | | | | | |
| | | kubeconfig | | | | | | |
| | +<-------------------+ | | | | | |
| | | | | | | | | |
| +------+----+ kubeconfig +------+-----+ | | +------+-----+ |
| |<--------------------------------------------------------| |
| | | |
+---------------------------------------------------+ +------------------+
If using a service account to connect to the API server, the ingress-controller expects the file
/var/run/secrets/kubernetes.io/serviceaccount/token to be present. It provides a secret
token that is required to authenticate with the API server.
Verify with the following commands:
# start a container that contains curl
$ kubectl run -it --rm test --image=curlimages/curl --restart=Never -- /bin/sh
# check if secret exists
/ $ ls /var/run/secrets/kubernetes.io/serviceaccount/
ca.crt namespace token
/ $
# check base connectivity from cluster inside
/ $ curl -k https://kubernetes.default.svc.cluster.local
{
"kind": "Status",
"apiVersion": "v1",
"metadata": {
},
"status": "Failure",
"message": "forbidden: User \"system:anonymous\" cannot get path \"/\"",
"reason": "Forbidden",
"details": {
},
"code": 403
}/ $
# connect using tokens
}/ $ curl --cacert /var/run/secrets/kubernetes.io/serviceaccount/ca.crt -H "Authorization: Bearer $(cat /var/run/secrets/kubernetes.io/serviceaccount/token)" https://kubernetes.default.svc.cluster.local
&& echo
{
"paths": [
"/api",
"/api/v1",
"/apis",
"/apis/",
... TRUNCATED
"/readyz/shutdown",
"/version"
]
}
/ $
# when you type `exit` or `^D` the test pod will be deleted.If it is not working, there are two possible reasons:
-
The contents of the tokens are invalid. Find the secret name with
kubectl get secrets | grep service-accountand delete it withkubectl delete secret <name>. It will automatically be recreated. -
You have a non-standard Kubernetes installation and the file containing the token may not be present. The API server will mount a volume containing this file, but only if the API server is configured to use the ServiceAccount admission controller. If you experience this error, verify that your API server is using the ServiceAccount admission controller. If you are configuring the API server by hand, you can set this with the
--admission-controlparameter.Note that you should use other admission controllers as well. Before configuring this option, you should read about admission controllers.
More information:
If you want to use a kubeconfig file for authentication, follow the deploy procedure and
add the flag --kubeconfig=/etc/kubernetes/kubeconfig.yaml to the args section of the deployment.
Gdb can be used to with nginx to perform a configuration dump. This allows us to see which configuration is being used, as well as older configurations.
Note: The below is based on the nginx documentation.
- SSH into the worker
$ ssh user@workerIP- Obtain the Docker Container Running nginx
$ docker ps | grep nginx-ingress-controller
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
d9e1d243156a quay.io/kubernetes-ingress-controller/nginx-ingress-controller "/usr/bin/dumb-init …" 19 minutes ago Up 19 minutes k8s_nginx-ingress-controller_nginx-ingress-controller-67956bf89d-mqxzt_kube-system_079f31ec-aa37-11e8-ad39-080027a227db_0- Exec into the container
$ docker exec -it --user=0 --privileged d9e1d243156a bash- Make sure nginx is running in
--with-debug
$ nginx -V 2>&1 | grep -- '--with-debug'- Get list of processes running on container
$ ps -ef
UID PID PPID C STIME TTY TIME CMD
root 1 0 0 20:23 ? 00:00:00 /usr/bin/dumb-init /nginx-ingres
root 5 1 0 20:23 ? 00:00:05 /nginx-ingress-controller --defa
root 21 5 0 20:23 ? 00:00:00 nginx: master process /usr/sbin/
nobody 106 21 0 20:23 ? 00:00:00 nginx: worker process
nobody 107 21 0 20:23 ? 00:00:00 nginx: worker process
root 172 0 0 20:43 pts/0 00:00:00 bash- Attach gdb to the nginx master process
$ gdb -p 21
....
Attaching to process 21
Reading symbols from /usr/sbin/nginx...done.
....
(gdb)- Copy and paste the following:
set $cd = ngx_cycle->config_dump
set $nelts = $cd.nelts
set $elts = (ngx_conf_dump_t*)($cd.elts)
while ($nelts-- > 0)
set $name = $elts[$nelts]->name.data
printf "Dumping %s to nginx_conf.txt\n", $name
append memory nginx_conf.txt \
$elts[$nelts]->buffer.start $elts[$nelts]->buffer.end
end-
Quit GDB by pressing CTRL+D
-
Open nginx_conf.txt
cat nginx_conf.txt